Shalltear couldn't do anything until she got hit first
Ainz used the opertunity to use like 25 buffs
He used the chance to put down traps in the area
He also used the opertunity to get a free super tier spell opening attack on her
Not only that but the super tier spell he used was one she was weak to
Ainz tricked shalltear into using spells that did much less damage to him.
He then tricked her into thinking he didnt know about her abilities
That entire fight was just ainz out smarting her. if he had no prep time and she wasnt frozen so he could hit her with a super tier spell he would have lost that fight with or without all the equipment he borrowed.
Also he was able to wear touch me's armor because of a spell he used called perfect warrior